The headaches began for Gemma a few weeks before she became seriously ill.
But as her health worsened, three separate GP appointments resulted in the same advice - go home and rest, it's nothing serious.
Simon, who was off work with depression and anxiety, said that after the third appointment, Gemma vomited and 'her mum was really worried'.
He said: 'She wasn't happy that the doctor had sent her home.
'She rang my friend Dave, whose sister Meg is an eye surgeon, Meg spoke to her and said she must go to A&E. I could tell early on the demeanour of the doctors.
'On the Tuesday at 4am the doctor came through and said her blood was deranged with cancer. I fainted.'
He said he went home, got their son Ethan ready for school and 'told him mummy wasn't well'.
They recorded a get well video message. Then, as he and Gemma's sister Rebecca were driving to hospital in Reading, Gemma texted to say she was being transferred to Oxford, where there was a special bit of equipment that she needed.
Simon said: 'We got there and we were blue-lighted to Oxford. I knew then how serious it was. Her chemotherapy started that night. Her consultant Dr Andy Peniket sat with us and told us she had acute myeloid leukaemia.
'He told us how it would only have fired up in the last few weeks, and we asked the survival chances - he said 50/50.
'It was heart-stopping. I'm glad we didn't Google it because it gave us the Wednesday and the Thursday as days when we were really close and I could look after her without panicking.
'Dr Peniket made us aware that the twice-a-day chemotherapy could be fatal.
'I slept by her side in the ward. That Thursday night she was quite uncomfortable. I think I took her to the loo early on Friday and she was a bit confused.
'That was the last time I spoke to her. I never had a chance to say goodbye or to chat about life going forward.
'The day cartwheeled out of control. She was taken for a head scan. When the blood was at its thickest it had caused undetectable damage to the membranes of the blood vessels in the brain, and as the chemotherapy began to do its job of thinning the white blood cells, the blood started to flow out of those damaged vessels. There were 15-20 separate bleeds.
'I was taken into the room of doom. I was given the news that she had hours to live. He said to bring Ethan. He came in and family and friends came in.
'She died surrounded by a lot of love.'
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here